feat: M1 foundation — compose stack, FastAPI, Google OAuth, encrypted tokens

- docker-compose with Postgres 16 + slim Python API image
- FastAPI app with session middleware, health endpoint, static login page
- Google OAuth (Authlib) with email invite-list whitelist; admin role support
- User + OAuthToken models; refresh tokens encrypted at rest (Fernet)
- Alembic migrations, run automatically on container startup
- Postgres backup/restore scripts for portability between machines

.dockerignore

@@ -0,0 +1,14 @@
+.git
+.gitignore
+.env
+*.env.local
+**/__pycache__/
+**/*.pyc
+.venv/
+venv/
+node_modules/
+frontend/dist/
+backups/
+*.dump
+README.md
+docs/